Switch for conveyor tracks



Jan. 13, 1948. c. L. SHEETS 2,434,523

SWITCH FOR CONVEYOR TRACKS Filed May 8, 1944 3 Sheets-Sheet 1 IN VEN TOR.

1m ld zw Jan. 13, 1948. c. SHEETS I 2,434,523

SWITCH FOR CONVEYOR TRACKS Filed May 8, 1944 3 Sheets-Sheet 2 IN VEN TOR.

- BY CZZILLJ/zeeiii 1 Jazz/10124 Jan. 13, 1948. c. L. SHEETS SWITCH FOR CONVEYOR TRACKS 7 Filed May 8, 1944 3 Sheets-Sheet 3 INVENTO'R. Caz/"Ll. 565656.

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Patented Jan. 13, 1948 SWITCH FOR CONVEYOR TRACKS Carl L. Sheets, Aurora, 111., assignor to Richards- Wilcox Manufacturing Company, Aurora, 111.,

a corporation of Illinois Application May 8, 1944, Serial No. 534,663

21 Claims. 1

The present invention is directed to an improved track switch for overhead conveyor tracks.

My invention is concerned primarily with improvements in the swinging tongue type of track switch, in contradistinction to the shifting stub type. In the swinging tongue type of switch the switching is performed over a movable track section which is pivoted at one end to the main line of track and which has its other end arranged for sidewise pivotal swinging motion into and out of registration with the different branch lines of track over which the traveling conveyor is to pass. In the shifting stub type of switch the switchin is performed over a straight section of track and one or more curved sections of track which are mounted side-by-side in a shiftable frame arranged for sidewise shifting movement for carrying the shiitable track sections by sidewise rectilinear motion into and out of registration with the main line of track and the selected branch line of track. The swinging tongue type of switch is much cheaper to construct and has fewer complications than the shifting stub type of switch. However, as heretofore constructed, the swinging tongue type of switch has been subject to the objection that the swinging tongue must be made quite long for a given distance of shifting movement between branch lines of track, and in many instances the required length of swinging tongue exceeds the space available for the switch, with the result that the shifting stub type must be employed because of its shorter fore and aft dimensions.

The general object of the present invention is to provide an improved swinging tongue type of switch which can be made of considerably shorter fore and aft dimension than those previously available. For example, one of the advantages of the invention is that it provides a switch which will operate in a space not greater than what would be required for a branch track connecting with the main line of track by a 90 curved section of track.

It is one of the more specific objects of the invention to make the swinging tongue of mul tiple hinge or multiple section construction so that when this switch tongue is swung laterally to one side or the other for lining up with a laterally disposed branch track, all of the change of direction will not occur over a single part of the switch tongue but, instead, one part of the change of direction will occur over one section of the switch tongue and another part of the change of direction will occur over another section of the switch tongue. Hence, the change of direction is accomplished more gradually and the tongue can therefore be made of shorter length. In the preferred construction herein shown, the switch tongue is made of two sections joined together by an intermediate hinge or pivot which is arranged so that it can have lateral swinging motion with the swinging motion of the outer end of the switch tongue, but to a lesser degree,

Another very important object of the invention is to provide improved means for locking this intermediate hinge or pivot in difierent selected positions of the switch tongue. For example, when the two sections of the articulated switch tongue have been swung to one lateral position or the other for lining up with a laterally disposed branch track, the articulating hinge between the tongue sections becomes locked against lateral shifting so that this intermediate hinge cannot become shifted out of its proper position as the loaded conveyor passes over the switch tongue. Similarly, when the articulated switch tongue is in a central or straight line position, this intermediate hinge between the tongue sections also becomes locked in this central position so that the tongue sections will not become accidentally deflected out of their proper positions as the loaded conveyor travels along the tongue sections.

Other objects, advantages, and features of the invention will appear from the following detailed description of one preferred embodiment thereof. In the accompanying drawings illustrating such embodiment:

Figure l is a plan view of one embodiment of the invention arranged for establishing switching connection with three branch tracks, this view showing the articulated switch tongue in the central or straight line position for lining up with the central or straight line track;

Figure 2 is a similar view showing the articulated switch tongue swung sidewise for lining up with one of the laterally extending branch tracks;

Figure 3 is a vertical longitudinal sectional view through the articulated switch tongue, corresponding to a section taken approximately on the plane of the line 3-3 of Figure 1;

Figure 4 is a vertical transverse sectional View through the stationary pivot at the inner end of the articulated switch tongue, corresponding to a section taken approximately on the plane of the line 4-4 of Figure 1; and

Figure 5 is a fragmentary horizontal sectional view taken flush with the top surfaces of the switching tongue sections, to show the arcuate matching ends of these sections.

Referring first to Figure 1, the switch structure is indicated in its entirety at Hi, this structure being interposed between a main line of track H and a plurality of branch tracks, indicated generally at l2, I3, and I4. Track I2 is a branch track curving to the left; track l3 is a straight through track extending coextensively with main track II, and track I4 is a branch track curving to the right. It will be understood that in some situations there will be only two of these three branch tracks |-2-|4. As shown in Figure 4, all "of't hese tracks are of I-beam section along the lower flange of which runs a wheeled trolley which carries the load. However, my invention is not confined to I-beam track sections, but can be used with other types of track section. In some instances the load carrying trolley may consist only of a pair of rigid side plates, with each side plate carrying either a single roller or a pair of rollers rolling on each outwardly extending bottom flange of the I-beam. However, in most instances the trolley will be of substantial length, comprising a load carrying beam or truss which is provided with swiveling pairs of trolley wheels at both ends of the truss, these pairs of wheels rolling along the lower outwardly extending flanges of the I-beam track. These trolley structures are so well known that they need not be illustrated. In some instances, the load carrying trolleys are hand propelled along the overhead conveyor tracks. In other instances, the load carrying trolleys are electrically driven, each comprising an electric motor connected with the trolley wheels so as to drive the load carrying trolley along the overhead conveyor track. In the electrically propelled type of trolley, it is customary'to supply the electric current through continuous conductor bars which extend parallel with each track rail, the trolley then having pick-up brushes or shoes which run along theseconductor bars. This arrangement of parallel conductor bars extending along the opposite sides of the supporting conveyor track is so well known-as not to require illustration. In these electrically energized systems, the space occupied by the parallel conductor bars greatly aggravates the track switch situation. When using a swinging tongue type of track switch, the space provided between the branch tracks l2, l3, 'and- |4-must be increased to accommodate these conductor bars. It will be seen that thegreater the spacing between the branch tracks [2, I3; and [4, the longer must be the old formof one-piece rigid switch tongue in order that the change of angle of this tongue will not be too sharp when swung into registration with a lateral branch track. However, the improved construction herein disclosed reduces the necessary length of 'the switch tongue very materially by dividing the tongue into articulated sections, so'that the change of angle is distributed over a plurality of joints, with the result that the angle at each joint'is substantially reduced.

Referring now to the detailed constructionof my improved tongue switch ID, the tongue of such switchis designatedZU in its entirety, this tongue comprising aninner short section a and an outer longer section 20b. These two tongue sections are-constructed of appropriate lengths of I-beam, preferably of substantially the same sectional contour as the conveyor tracks. The tongue in its entirety swings around a main or stationary pivot 2|; and the two sections of the tongue are articulated together by a pivot 22.

The frame of the switch structure comprises primarily an arcuate supporting bar of right anglecross section, two angle bars 26,26 which extend inwardly from the outer portions of the arcuate bar 25, and a connecting plate 2! to which the inner ends of the bars 26, 26' are welded. The branchtracks fl2, l3, and-l4 are attached to the arcuate supporting bar25 by angle brackets 29 which have their vertical legs welded to (Figure 3). "3| enables the attaching bolt 32 to be shifted laterally for adjusting the position of each branch t'ifack-vvith respect to the arcuate supporting bar 25. The arcuate bar 25 has outwardly projecting end portions 25' and 25" to which are secured-'guidebells'or funnels 34, 34' through which pass pullchains 35, 35' for actuating the switch tongue into its different switching positions. The manner in which these pull chains release .the main-locking detent will be later described.

The outer'end of each diagonal sidebar "26, ZGGis-Secured tothe horizontal flange of thearcuate supporting bar 25 by welding, or in any other suitable manner. The vertical flangeof each of these diagonal side bars carries an'adjustable stop screw 31, 31' for limiting the side wiseswinging motion of the switch tongue so as to bring the tongue into accurate registration with the curved branch tr'acks l2 and |4,'these stop-screws 31, 31" beingadju'stably mounted" by nuts 38 which enable the stop screws to be adjusted inwardly or outwardly.

Referring -noW to the pivoted mounting-of the two tongue sections 2lia'and' 20b, it will be seen from Figures 3 and 4 that the stationary pivot axis 2| for the inner tongue section 20a consists of'an upper pivot screw 2lq"and-a"lower pivot stud 2-lb disposed I inverti'cal axial alignment. The lower endof the pivot screW -ZIa'is welded to the top-flange 'of the -I--beam tongue section 20a, and assembled down *over this pivot screw isa pivot plate 4|, and superposed on "this pivot plate is-the transverse frame plate 21' to which the converging ends of "the side bars26, 26" are welded. Nuts 42 screw down 'over the top of the pivot+2|aand bear'against the frame plate 21. The pivot plate4| remainsstationary, and the tongue section2|laswive1s to right or left under this pivot plate. The-lower-pivot stud 2| 1), aligned with the upper pivot screw 2 Ia, is welded to astationary lowerpivotplate43. An enlarged headon the pivot stud 2|b seats in a circular cavity' 2| c formed in the under side of the lower flange of tonguesection'illla. The stationary upper and lower pivot plates 4| ana aa are secured to' the top and bottom flanges ofa short length of I-beam track 44 which'serves as a coupling section for-establishing coupled connectionwith the main line track II. The lower pivot plate43'is welded'to the under side of this coupling section-44. --A clamping stud 4'5=is welded in the upper flange of the coupling "section =44, andthe upper pivot plate 4| is assembled down over this clamping screw. A corresponding clampingscrew 46- is welded or otherwise secured 'to the upper flange of the main track l l, and a coupling'dolock- '41 is-dropped down-over the studs '45 and- 4B and clamped in place by-the nuts "48. A bottom joint plate 49 is welded to 'the underside'of the coupling section 44 and 'extends' under the end if the track H for interlocking with another pla'te 50 welded to the bottom oftrack-Il, these'two plates having cooperating interlocking-or aligning lugs,'as shown in Figure 1. A transverse bolt 5| extends 'crosswise'through the tie block 41 and carries nuts 52 at its ends which exertconverging pressureon a clamping yoke or'yokes' 53 which overliethe coupling block 4? and extend down and bear against the under sideof the' top flanges of coupling section 44 and main track II. It will be understood that the above described arrangement of coupling section 44, tie block 41, clamping yokes 53, etc., constitute one preferred arrangement for mounting the switch frame and the pivot axis 2| on the adjacent end of the main track H, but the invention is not limited to the use of this particular coupling arrangement, because other coupling constructions can also be employed.

The laterally swinging pivot axis 22, which connects the inner tongue section 20a to the outer tongue section 2%, comprises the upper pivot screw 22a and the lower pivot stud 22b both arranged in vertical alignment. The upper pivot screw 22a is welded to the top flange of the tongue section 201), and this screw extends upwardly in pivoting relation through an upper pivot plate 55 which is welded to the top of the tongue section 20a and extends forwardly over the top of the tongue section 201). The lower pivot stud 22b is welded to a bottom pivot plate 58 which is welded to the under side of the tongue section 2011 and extends forwardly under the tongue section 20b. The enlarged head of the pivot stud 222) seats in the circular cavity 5'! formed in the under side of the tongue section 201). It is desirable that the degree of sidewise swinging movement of the pivot axis 22 to each side of the central position be limited so as to insure that the inner tongue section 29a will only swing through part of the total change of direction, with the outer tongue section 2% swinging through the remainder of the change of direction. To this end, the pivot screw 22a extends upward- 1y through an arcuate slot 6! formed in the horizontal flange of a curved angle bar 62 which extends between and is welded to the diagonal side bars 26, 26'. The guide slot BI is curved on a radius struck from the center of the stationary pivot axis 2!, as indicated by the dotted line radius designated 1' in Figures 1 and 2, and the length of this slot is such that when the switch tongue is swung to one of its lateral positions the inner tongue section 20a is limited in its lateral movement so that it only partakes of approximately one-half of the total change of direction, the remaining half of the change of direction being taken by the outer tongue section 2512. This distributes the angle between the suc- V cessive sections of the main track and switch track so that there will be no binding of a relatively long wheeled trolley traveling along the overhead conveyor. A nut 63 and washer engaging over the pivot screw 22a bear on the angle bar 62 so that the hinge axis 22 is supported against sagging downwardly under the weight of a heavily loaded trolley. Referring to Figure 5, which is a horizontal section taken flush with the top surfaces of the track sections, it will be seen that at the stationary hinge axis 2| the top and bottom flanges of the coupling track section 44 have arcuate recesses '66 into which extend arcuate end portions 61 on the top and bottom flanges of the inner tongue section 20a, these recesses and end portions being concentric with the hinge axis 2|. Similarly, at the swinging hinge axis 22, the top and bottom flanges of the inner tongue section 29a have arcuate recesses 68, and the corresponding flanges 0f the outer tongue section 20b have arcuate end portions 69 matching therewith. These arcuate matching end portions at both hinge axes aiiord substantially continuous flange surfaces over which the supporting wheels of. the load carrying trolleys can roll at the hinge joints of the switch. Referring to Figure 3, it will be seen that the vertical web portions of the two tongue sections are notched back at H and 12 to avoid interference with the web portions of the contiguous track sections.

The switch tongue 20 is shifted between its different switching positions through the instrumentality of the pull chains 35, 35' which hang down to a point conveniently accessible from the floor level. Pull exerted on either of these two chains is first efiective to release a conventional spring latch, indicated in its entirety at 75. This spring latch serves to latch the swinging end of the switch tongue in registration with the selected one of either of the branch tracks l2, 13, or M. The latch assembly comprises a base casting 15 which is secured by bolts TI to the upper flange of the outer tongue section 2%. The outer end of the casting 16 extends forwardly in the nature of a supporting lip to ride on the upper surface of the horizontal flange of arcuate supporting bar 25. If desired, rollers or other antifriction devices may be secured to the casting 16 to ride on the horizontal flange of the bar 25. A spring-pressed latching bolt 18 is guided in the casting I6 and is adapted to be projected out wardly through latching holes 19 formed in alignment in the vertical flange of arcuate supporting bar 25 and the vertical flange of the angle bracket 29. One of these locking holes 19 is provided in alignment with each of the branch tracks l2, l3, and 14 so as to lock the outer end of the switch tongue in registration with any selected one of these branch tracks. The latching bolt 18 is normally pressed outwardly by a compression spring 8| encircling the rear portion of the bolt shank. The bolt is adapted to be retracted to releasing position by the sidewise swinging motion of a T-shaped releasing yoke 82 which is pivotally mounted on the outer end of the bolt shank by a vertical pivot pin 83. The pull chains 35 and 35' are connected to the forwardly extending arm of this releasing yoke. Two oppositely projecting cam arms 82, formed on the rear portion of the yoke, are adapted to engage against a flat rear face of the casting 16. When pull exerted through either of the pull chains 35 or 35' swings the re leasing yoke 82 about the pivot pin 83, the oppositely projecting cam arm 82' exerts camming pressure against the rear face of the casting l6 and thereby exerts retractive effort on the latching bolt 18 for pulling the bolt out of the locking hole 19 associated with that particular branch track. Immediately upon the release of the latching bolt the switch tongue is thereafter free to swing laterally in the direction of pull exerted by the chain which has efiected the releasing. In this manner, the switch tongue can be moved selectively between any of the three positions corresponding to the three branch tracks l2, l3, and [4. As previously described, the lateral throw of the switch tongue is limited by the stop screws 31, 31' for stopping the switch tongue in registration with the branch tracks l2 and HI. In the event that the switch is used only with two branch tracks, such as the central track 13 and the right hand branch track 14, then a stop screw 3'!" (as shown in dotted lines) may be secured to the arcuate supporting bar 25 in position to stop the left hand movement of the switch tongue at a point in registration with the straight line track [3.

Rigidly secured to the outer tongue section 2021 is a safety stop plate or blind 85 which serves to block off the open ends of the branch tracks [2;

games 7 l3, and 14 when the switch tongue is not in reg, istration with that particular branch track. This step plate or blind is shown as being bolted between the tongue section 20b and the base casting 16 of the latch mechanism 15, such safety stop plates or blinds being old and well known.

Referring now to my improved locking mechanism for locking the swinging pivot 22 in each of the three selected positions of the switch tongue, this locking mechanism comprises an arcuate locking surface 86 of predetermined curvature formed along the outer flanged surface of the curved angle bar 62. This surface is an arc struck from the center at, which center is located'intermediate the stationary hinge axis 2| and the arc of swinging movement of the swinging hinge axis 22, this center x being preferably slightly closer to the stationary hinge axis 2 The arcuate surface 86 extends over a span of approximately 80 degrees indicated as the 'arc' subtended between the radial arrows y and 2', although it will be understood that for different degrees of movement or the switch tongue under different operating conditions this arcuate span may be increased or decreased, if desired. The ends of the arcuate surface 86 are shown as extending by straight line surfaces 87 and 88 over to points of intersection with the diagonal side bars 26, 26'.

Traveling over the arcuate surface 86 is a pair of locking rollers 89 and 98 which are symmetrically disposed with respect to the median line of the outer tongue section 2012. These rollers are rotatably mounted on upwardly extending pivot studs 9| and 92 anchoredin the' mounting plate 83 which is secured by bolts or cap screws 94 to the top flange of the oute'r'tongue section 28b.

When the articulated switch tongue is disposed in the central position illustrated in Figure 1, the two rollers 89 and 98 serve to lock the articulating hinge axis 22 against sidewise movement, this occurring by reason of a binding or cramping action which occurs between the rollers 89 and 9 and the arcuate surface 86 whenever the hinge axis 22 tends to swing either to left or right. For example, if a heavily loaded trolley traveling along the conveyor track should exert a momentary force tending to swing the articulating axis 22 to the right, it will be obvious that the inner end of the switch tongue will remain anchored by the stationary pivot axis 2| and the outer end of the'switch tongue will remain anchored by the spring latch 15, with the result that such deflection force toward the right can brily tend to fold the two tongue sections toward the right at the articulating axis 22. Any tendency to move in this direction immediately cramps the left'hand roller 89 laterally or inwardly against the arcuate surface 86. Because this arcuate surface is of a shorter radius than the radial distance from the center of roller 89 to stationary pivot axis-2 this roller is prevented from following the are that it would have to follow if it were to swing around the stationary pivot axis 2|. Hence, a binding action occurs between the roller 89 and the looking surface 86 which looks the roller 89 against movement to theright over the arcuate surface 86. If the deflection force should act in the reverse direction toward the left, the same looking or binding action occurs between the right hand roller 90 and the arcuate locking surface 86, in a reverse direction. Thus, with the articulated switch tongue in this central position, andlatchecl at its outer end by the spring latch mechanism 15, the articulating hinge axis 22 is locked against accidental sidewise movement. At this time, the

locking action is comparable in some respects to, the use of a centrally disposed hump for preventing the rollers 89 and from moving past the hump in either direction.

Let us assume now that the right hand pull chain 35' has been pulled for swinging the switch tongue over into registration with the right hand branch track l4. As soon as the spring latch 15 has become released, the outer end of the outer tongue section 20b starts swinging toward the right. Some'of this swinging movement will be taken up at the swinging pivot 22 and some at the stationary pivot 2|. The outer end of the outer tongue section will tend to lead or move in advanc of the swinging pivot 22, with the result that the left hand roller 89 will be oscillated in a direction outwardly or away from the arcuate surface 86 and the right hand roller 98will be oscillated in a direction toward the surface 88. There is some relatively small play between the parts, and this play is just sufficient so that this outward oscillation of the left hand roller 89 will enable it to clear the hump of the arcuate surface 86 for permitting the shiftable pivot 22 to shift over into abutment against the right hand end of the slot 8 At this time, the right hand roller 98 is partaking of a compound pivotal movement, part of which occurs around the stationary pivot axis 2|, and part of which occurs around the movable pivot axis 22, and hence this'right hand roller does not exert any binding action against the surfaces 88 and 88 whichwould prevent shifting of the movable pivot 22 to the right. When this movable pivot is in abutment against the right hand end of the slot 6i, this endof the slot positively locks the pivot against any further movement to the right. At this time, the outer end of the outer tongue section is held by the spring latch 15 in registration with the right hand branch track M. Hence, any tendency of the movable pivot 22 to shift to the left necessarily requires that the outer tongue section 28b then swing about a pivot center located approximately in the latching hole 19 in registration with the right hand branch track I4. Obviously, any such tendency of the outer tongue section to swing about a pivot center at this outwardly disposed point tends to cramp 01' wedge the right hand roller 98 inwardly against the locking surface 86. The roller 90 cannot swing to the left if such swinging movement requires pivoting around a center near the outer end of the outer switch section. Hence, the shiftable pivot 22 remains locked against shifting movement'to theleft as long as the outer track section remains latched in' the latching hole of the right hand branch track H. In the operation of swinging the switch tongue back to its central position the outer end of the outer tongue section precedes'orswings in advance of the shiftable pivot 22, with the result that the right hand roller 98 is swung outwardly away from the arcuate surface 86 so that it does not exert the aforementioned binding or cramping action against this surface. The two sections of the tongue then move back to the central position first described, in which position the shiftable pivot 22 is held against accidental lateral move ment by the conjoint action of the two rollers 89 and 98 engaging on opposite sides of the hump of the arcuate surface 86. It will be obvious that when the switch tongue is swung to the left into registration with the left hand branch track, |2, the left hand roller 89 performs the same locking function for holding the shiftable pivot 22 against accidental shifting movement as was described above in connection with the right hand roller 99 when the switch tongue was in the right hand position. Thus the two rollers 89 and 90 function as cramping devices for performing the above holding functions on the shiftable pivot 22.

While I have illustrated and described what I regard to be the preferred embodiment of my invention, nevertheless it will be understood that .such is merely exemplary and that numerous modifications and rearrangements may be made therein without departing from the essence of the invention. For example, while I prefer to extend the upper pivot pin 22a upwardly through the arcuate slot 6! in the curved angle bar 62, substantially the same effect could be obtained by having this pivot pin terminate flush with the top of the upper pivot plate 55, and then rigidly securing a Z-shaped or offset angle bracket to the pivot plate 55 with th raised flange or lug of said bracket extending up over the horizontal flange of the curved angle bar 52 to ride thereon in the sidewis motion of the movable pivot 22, this sidewise motion being limited by laterally spaced stop pins which would project up from the horizontal flange of the curved angle bar 62 for limiting lateral motion of said raised flange or lug in the same manner as is done by the pin 22a and slot 6| of th illustrated embodiment. Furthermore, while I prefer to use rollers as the spaced locking members 89 and 96, nevertheless plain studs, pins, or other corresponding locking devices may be employed instead or rollers.

I claim:

1. In a track switch of the class described, the combination of a switch tongue swinging around a substantially stationary pivot axis for enabling the outer end of the said switch tongue to be brought into registration with different branch tracks, said switch tongue comprising inner and outer sections articulated together by a swinging pivot, latching means for holding the outer end of said switch tongue in the different switching positions of said tongue, and locking mechanism separate from said latching means for holding said swinging pivot in the different switching positions of said tongue, said locking mechanism comprising a curved locking surface and cramping means adapted to exert a cramping force thereon.

2. In a track switch of the class described, the combination of a switch tongue swinging around a substantially stationary pivot axis for enabling the outer end of said switch tongue to be brought into registration with different branch tracks, said switch tongue comprising inner and outer sections articulated together by a swinging pivot arranged for swinging movement through an are substantially concentric of said stationary pivot axis, latching means for holding the outer end of said switch tongue in the different switching positions of said tongue, and automatic locking mechanism separate from said latching means governed by the relative articulation between said tongue sections for holding said swinging pivot in the different switching positions of said tongue, said locking mechanism being disposed between said swinging pivot and said latching means and comprising a stationary arcuate looking surface and cooperating clamping means having traveling contact over said locking surface, said cramping means being adapted to exert a holding action on said swinging pivot by cramping engagement against said arcuate locking surface.

3. In a track switch of the class described, the,

combination of a switch tongue swinging around a substantially stationary pivot axis for enabling the outer end of said switch tongue to be brought into registration with different branch tracks, said switch tongue comprising inner and outer sections articulated together by a swinging pivot arranged for swinging motion through an arc concentric of said substantially stationary pivot axis, latching means for holding the outer end f said switch tongue in different switching positions of said tongue, and means for locking said swinging pivot in a shifted position comprising a locking surface formed on a curve eccentric with respect to the path of motion of said swinging pivot, and a member carried by one of said tongue sections adapted to travel over said locking surface in a normal operation of said switch but operative to bind against said locking surface if said swinging pivot should accidentally tend to move out of a predetermined switching position.

4. In a track switch, the combination of a switch tongue comprising tongue sections articulated together by a swinging pivot, a locking surface curved eccentrically with respect to the swinging motion of said pivot, and spaced locking members carried by one of said tongue sections and adapted to have locking coaction with said locking surface to hold said swinging pivot against accidental movement.

5. In a track switch for overhead conveyor tracks, th combination of a, switch tongue comprising tongue sections articulated together by a swinging pivot, and mechanism for locking said swinging pivot against accidental movement in different shifted positions f said switch tongue comprising a stationary curved locking surface curved eccentrically with respect to the swinging motion of said pivot, and a pair of spaced locking members movably carried by one of said tongue sections and adapted to have locking coaction with said locking surface 6. In a track switch for overhead conveyor tracks, the combination of a switch tongue comprising tongue sections articulated together by a swinging pivot, and mechanism for locking said swinging pivot against accidental movement in different shifted positions of said switch tongue comprising a curved locking surface curved on a radius of shorter length than the radius of swinging movement of said pivot, and a plurality of rollers carried by one of said tongue sections and adapted to have locking coaction with said curved locking surface.

7. In a track switch for overhead conveyor tracks, the combination of a switch tongue com-' prising inner and outer tongue sections articulated together by a swinging pivot, said tongue sections being movable from a substantially straight line position to a laterally shifted posi' tion, and automatic locking mechanism for holding said swinging pivot against accidental swinging movement from one of said positions'to the other comprising a curved locking surface, and a plurality of locking members carried by said outer tongue section and adapted to have locking coac tion with said locking surface.

8. In a track switch for overhead conveyor tracks, the combination'of a switch tongue comprising an inner tongue section swinging around a relatively stationary pivot and an outer tongue section connected to said inner tongue section by a swinging pivot, and locking mechanism for look ing said swinging pivot against accidental swinging movement comprising a curved locking surface curved on a radius struck from a center intermediate said stationary pivot and said swinging pivot, and a pair of locking members carried by said outer tongue section adapted to have looking coaction with said curved locking surfa e.

'9. In a swinging tongue track switch for overhead conveyor tracks. the combination of a. swi ch tongue comprisin an inner tongue section swinging around a relatively stationary pivot and an outer tongue section connected to said inner tongue section by a swinging pivot, said tongue sections being movable from a substant ally straight line position to a laterallyshifted position, and utomatic locking mechanism for holding said swinging pivot against accidental swinging movement from one of said positions to the other of said ositions. said lock n mechanism comprising a stationary arcuate locking surface curved on a radius of shorter length than the radius of swinging movement of said swinging pivot and struck from a center disposed intermediate said stationary pivot and said swinging pivot, and a pair of locking members carried by said outer tongue section in laterally spaced relation to said sw nging ivot and ada ted to have locking coaction with said arcuate locking surface, whereby if the swinging pivot tends to precede the outer end of said outer section in moving from one position to ano her the trailing one of said pair of locking members is cramped inwardly against said curved locking surface to prevent any substantial movement of said swinging pivot inthis direction. 10. In a track switch of the ton ue type for overhead conveyor tracks, the combination of a switch tongue comprising an inner tongue section swinging around a relatively stationary pivo and an outer tongue section articulated to said inner tongue section by a swinging pivot, said tongue sections being movable in either direction from a substantially straight line central position to either one of two laterally shifted positions, and automatic locking mechanism for holding said swinging pivot against accidental swinging movement from said central position to either of said laterally shifted positions, or from either of said lateral y shifted positions to said central pos tion, said locking mechanism comprising a stationary arcuate locking surface curved on a shorter radius than the radius of swinging movement of s id swinging pivot and struck from a center which is disposed intermediate said stationar pivot and said swinging pivot along the medial line of said swi ch tongue when the latter is in its ce tral straight line position. and a pair of locking rollers carried by. said outer tongue section adapted to have locking coaction with said arcuate lo king surace on opposite sides of said medial line when said ton ue is in said strai ht line central position. said rollers coacting with said arcua e lo"king surface whereby it the swinging pivot tends to precede the outer end of said outer ton ue sect on in moving from said central position to either la erally disposed posi ion, or from ei her la era ly di posed position back tosaidlcentrally di po ed position the trailing roller of said pair of ro lers is cramped inwardly against said curved locking surface to prevent anysubstantialmovement of said swingin pivot in advance of the ou er end of said outer tongue section.

1l In a track switch for overheadconveyor tracks, the combination of a switchtongue comprising tongue sections articulated together by a swinging pivot. said tongue sections being movable from a substantial y straight line position to a laterally shifted position, stop means for limiting the outward movement of said swinging pivot when said tongue sections are in said laterally "shifted position, and mechanism for preventing accidental inward shifting movement of said swinging ivot from said laterally shifted position toward said substantially straight line position, said mechanism comprising a stationary curved lock ng surface disposed adjacent to the path of movement of said swinging pivot, and roller means carried by one of said tongue sections adapted to exert a binding force against said curved locking surface if said moving pivot tends to precede the outer end of said outer tongue section in swinging from said laterally disposed position to said substantially straight line position,

12, In a track switch of the swinging tongue type for overhead conveyor systems, the combination of a switch tongue swinging around a substantially stationary pivot for enabling the outer end of said switch tongue to be brought into registration with different branch tracks, said switch tongue comprising inner and outer sections articulated together by a swinging pivot arranged for swinging motion through an arc concentric of said substantially stationary pivot axis. latching means for holding the outer end of said switch tongue in the difierent switching positions of said tongue, a supporting member having an arcuate slot formed therein struck from a center subsantially coincident with said stationary pivot, said swinging pivot swinging sidewlse in said arcuate slot, an arcuate locking surface on said latter member curved around a center disposed intermediate said stationary pivot and said arcuate slot, and a pair of rollers carried by said outer tongue section adapted to travel over said arcuate locking surface, said rollers being spaced laterally equal distances from the longitudinal medial line of said outer tongue section and arranged whereby any lateral force tending to cause said swinging pivot to move laterally in advance of the outer end of the outer section causes the trailing roller of such pair to cramp inwardly against said curved locking surface and thereby prevent such swinging movement of said swinging pivot in advance of the outer end of said outer tongue section.

13. In a track switch of the tongue type for overhead conveyor tracks, the combination of a switch tongue comprising a pair of tongue sections adapted to distribute the total swiching deflection of the tongue between said sections, a moving pivot connecting two of said sections, supporting means having an arcuate slot therein for supporting said moving pivot and limiting its range of movement, and automatic means for locking said moving pivot in difierent shifted positions of said switch tongue.

14. In a swinging tongue type of track switch for overhead conveyor tracks, the combination of a switch tongue comprising inner and outer tongue sections, a stationary pivot around which said inner tongue. section swings, a moving pivot connecting said two sections and around which said outer section swings, spring latch means for latching the outer end of said outer tongue section in registration with the difierentbranch tracks, and means comprising an arcuate slot l miting the range of sidewlse movement of said swinging pivot for compelling the total switching deflec ion of said tongue to be distributed between said two tongue sections.

15. In a track switch of the class descri ed for overhead conveyor tracks, the combination. of a stationary coupling section of track an inner switching tongue section, a stationary pivot connecting said inner tongue section with said coupling section, cuter switching tongue section, a swinging pivot connecting said outer tongue section with said inner tongue section, supporting means for said moving pivot comprising an arcuate slot struck from a center substantially coincident with said stationary pivot, said swinging pivot being movably suspended in said arcuate slot, latch means for releasably latching the outer end of said outer tongue section in registration with different branch tracks, said coupling section and said two tongue sections being of corresponding I-beani cross section, and matching arcuate portions formed in the lower flanges of said sections at said stationary pivot and at said moving pivot, each of said matching portions comprising an arcuate recess formed in one flange and an arcuate extension portion formed in the other flange and extending into said arcuate recess.

16. In a swinging tongue type of track switch for overhead conveyor systems, the combination of a switch tongue, means for coupling the inner end of said switch tongue with the main line of track, an arcuate supporting bar for supporting the outer end of said switch tongue for lateral swinging movement into and out of registration with a plurality of branch tracks, latch means for latching the outer end of said switch tongue to said arcuate supporting bar in registration with said difierent branch tracks, said switch tongue comprising inner and outer tongue sections articulated together by a swinging pivot, and means coacting with said swinging pivot for compelling the total switching deflection of said switch tongue to be distributed between said inner and outer tongue sections, said latter means comprising an arcuate slot in which the upper end of said swinging pivot is movabiy suspended.

17. In a track switch for overhead conveyor tracks, the combination of a switch tongue comprising inner and outer tongue sections articulated together by a swinging pivot, said tongue sections being movable from a substantially straight line position to a laterally shifted position, means for supporting said swinging pivot against downward stresses, and automatic locking mechanism for holding said swinging pivot against accidental swinging movement from one of said positions to the other comprising a curved locking surface, and a plurality of locking members carried by said outer tongue section and adapted to have locking coaction with said locking surface.

18. In a swinging tongue track switch for overhead conveyor tracks, the combination of a switch tongue comprising an inner tongue section swinging around a relatively stationary pivot and an outer tongue section connected to said inner tongue section by a swinging pivot, said tongue sections being movable from a substantially straight line position to a laterally shifted position, and automatic locking machanism for holding said swinging pivot in each of said different positions, said locking mechanism comprising pin and slot means supporting said swinging pivot, a stationary arcuate locking surface curved on a radius of shorter length than the radius of swinging movement of said swinging pivot and struck from a center disposed intermediate said stationary pivot and said swinging pivot, and locking means carried by said outer tongue section and adapted to have locking coaction with said arcuate locking surface.

19. In a track switch of the swinging tongue type for overhead conveyor systems, the combination of a switch tongue swinging around a substantially stationary pivot for enabling the outer end of said switch tongue to be brought into registration with difierent branch tracks, said switch tongue comprising inner and outer sections articulated together by a swinging pivot arranged for swinging motion through an arc concentric of said substantially stationary pivot axis, a supporting member having an arcuate slot formed therein struck from a center substantially coincident with said stationary pivot, said swinging pivot comprising a pin swinging sidewise in said arcuate slot, an arcuate locking surface curved around a center disposed intermediate said stationary pivot and said arcuate slot, and a pair of laterally spaced projecting members carried by said outer tongue section adapted to travel over said arcuate locking surface and adapted to exert a binding force against said arcuate locking surface if said swinging pivot tends to precede the outer end of said outer tongue section in swinging from one selected track switching position to another.

20. .In a swinging tongue type of track switch for overhead conveyor tracks, the combination of a switch tongue comprising inner and outer tongue sections, a stationary pivot around which said inner tongue section swings, a moving pivot connecting said two sections and around which said outer section swings, latch means for latching the outer end of said outer tongue section in registration with different branch tracks, and supporting means having an arcuate slot therein in which said moving pivot swings in the movement of said switch tongue.

21. In a track switch of the class described, the combination of a switch tongue swinging around a substantially stationary pivot axis for enabling the outer end of said switch tongue to be brought into registration with different branch tracks, said switch tongue comprising inner and outer tongue sections articulated together by a swinging pivot, latching means for holding the outer end of said switch tongue in the different switching positions of said tongue, means coacting with said swinging pivot for compelling the total switching deflection of said switch tongue to be distributed between said inner and outer tongue sections, and locking mechanism separate from said latching means for holding said swinging pivot in the different switching positions of said tongue, said locking mechanism comprising a curved locking surface and cramping means adapted to exert a cramping force thereon.

CARL L. SHEETS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,602,378 Harris Oct. 5, 1926 1,602,379 Lawrence Oct. 5, 1926 1,759,378 Thompson May 20, 1930 979,469 Gilman Dec. 27, 1910 1,340,208 Beaty May 18, 1920 

